Add the contents of disk 1

- LHA -lh5/-lh6/-lh7 decoding with CRC checks (disk 1 is mostly lh5)
- Real track palettes and set names, read from each track file's header
- Camaro, plus the caravan as a towable trailer (Caravans option)
- Drivers' names, menu pictures and the original .set values per car
- Original sound effects (IFF 8SVX) through a new sample mixer: engine
  pitched with revs, tyre screech, crashes, backfire, horn, start beeps
- The original tune (OctaMED MMD1) through a new player; loudness tracks
  OpenMPT's render through the whole song. Music option in the menu
- Title picture (IFF ILBM) at the top of the menu
- skids unpack and skids music commands
- Gate crossings now judged on each car's whole movement per frame,
  including collision knocks; stalled computer cars are put back on the
  line after 8 seconds

The executable's game logic (handling, AI) is still not decoded.

assets/tracks/track3-6/track.txt

@@ -47,6 +47,9 @@ gate 796.78125 544.59375 896.84375 523.4375
 gate 760.125 503.53125 816.78125 446.34375
 gate 658.5 417.5 705.75 366.25
 
+# Name of the set of tracks this one belongs to, shown in the menu.
+set Surf 'n' Slam
+
 # As stored in the original data; not used by the game.
 start 356 188
 flags 0